Title: Photosynthesis
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2Outline
- Protist Biology
- Protist Evolution
- Protist Diversity
- Green Algae
- Red Algae
- Brown Algae
- Diatoms
- Dinoflagellates
- Protist Diversity, cont.
- Euglenoids
- Zooflagellates
- Pseudopods
- Ciliates
- Sporozoans
- Slime Molds
- Water Molds
3General Biology of the Protists
- Classified into the Domain Eukarya the Kingdom
Protista - Morphology
- Most unicellular
- Many with amazingly high level of strucrural and
functional complexity - Life cycles
- Asexual reproduction common
- Sexual reproduction may occur when conditions
deteriorate - Some life cycles simple, many extremely complex
4Origin of the Eukaryotic Cell
5Ecology of Protists
- Protists are of enormous eco-logical importance
- Photoautotrophic forms
- Produce oxygen
- Function as producers in both freshwater and
saltwater ecosystems - Major component of plankton
- Organisms that are suspended in the water
- Serve as food for heterotrophic protists and
animals - Many protists are symbionts
- Ranges from strict parasitism to mutualism
- Coral reefs greatly aided by symbiotic
photoautotrophic protists in tissues of corals
6Evolution of Protists
- Complexity and diversity of protists makes them
difficult to classify - Many classification schemes proposed
- None has broad support
- Cannot be classified as plants, animals, or fungi
- Could be split into as many as a dozen kingdoms
- The scheme chosen for this discussion is based on
modes of nutrition
7Protist Diversity
8Diversity of ProtistsGreen Algae The
Chlorophyta
- Phylum Chlorophyta
- Approximately 7,500 species
- Inhabit a variety of environments including
oceans, freshwater, snowbanks, tree bark, and
turtles backs - Many are symbionts with fungi, plants, or animals
- Morphology varied
- Majority unicellular, but many are filamentous or
colonial - Some are multicellular and resemble leaves of
lettuce - Plants thought to be derived from Chlorophyta
because both groups - Have a cell wall that contains cellulose
- Possess chlorophylls a and b, and
- Store excess food as starch
9Green AlgaeChlamydomonas
- A minute (lt25 ยต m), actively moving flagellate
- Inhabits still, freshwater pools
- Fossil ancestors date back over a billion years
- Anatomy
- Definite cell wall
- Single, large, cup-shaped chloroplast
- Chloroplast with a pyrenoid where starch is
synthesized - Many with a bright red eyespot, or stigma on
chloroplast - Two long, whip-like flagella
- Project from the anterior end
- Operate with a breaststroke motion
10Electron Micrograph of Chlamydomonas
11Green AlgaeChlamydomonas
- Most often reproduces asexually
- As many as 16 daughter cells within parent cell
- Escape by digesting the parent cell
- Occasionally reproduces sexually
- Gametes fuse to form a zygote
- Becomes a heavy-walled, resistant zygospore
- Goes into a period of dormancy
- Upon germination produces four zoospores by
meiosis - Spore - a reproductive cell that develops into
a new organism without fusing with another cell - Zoospore - flagellated spores, typical of
aquatic species
12Reproduction in Chlamydomonas
13Green AlgaeSpirogyra
- Filamentous green algae
- Found in green masses on the surfaces of ponds
and streams - Has ribbon-like, spiraled chloroplasts
- Sexual reproduction by conjugation
- A temporary union during which the cells exchange
genetic material - Two filaments line up parallel to each other
- Cell contents of one filament move into the cells
of the other filament - Forms diploid zygospores
- In spring, undergo meiosis to produce new haploid
filaments
14Spirogyra
15Green AlgaeMulticellular Forms
- Ulva
- Multicellular green alga
- Commonly called sea lettuce
- Thallus (body) is two cells thick
- Can be as much as a meter long
- Sexual cycle involves alternation of generations
- Similar to higher plants, except
- Both generations look exactly alike, and
- The gametes all look the same
16Multicellular Green Algae
17Green AlgaeColonial Forms
- Volvox
- A colony is a loose association of independent
cells - A Volvox colony
- A hollow sphere
- Thousands of cells arranged in a single layer
surrounding a watery interior - Each cell of colony resembles a Chlamydomonas
cell - Flagella beat in a coordinated fashion
- Some cells are specialized for reproduction
- Each can divide asexually to form a new daughter
colony within the parental colony - Leaves parental colony by releasing an enzyme
that dissolves away a portion of the parental
colony
18Volvox
19Diversity of ProtistsRed Algae The Rhodophyta
- Multicellular
- About 5,000 species
- Live mostly in warmer seawater, some as deep as
200 m - Economic Importance
- Agar - capsules dental impressions cosmetics
culture medium electrophoresis food prep. - Carrageen - an emulsifying agent used in
chocolate, low-fat foods, cosmetics - The reddish-black wrappings around sushi rolls
consist of processed Porphyra blades
20Red Algae
21Diversity of ProtistsBrown Algae The
Phaeophyta
- About 1,500 species
- Most live in colder ocean waters along rocky
coasts - No unicellular or colonial brown forms
- Morphology
- Some small forms with simple filaments
- Others large multicellular forms that may exceed
200 m in length - Pigments
- Chlorophylls a and c
- Fucoxanthin (a type of carotinoid pigment) gives
them their color - Excess food stored as a carbohydrate called
laminarin
22Brown Algae
23The Phaeophyta
- Multicellular forms of green, red, and brown
algae are called seaweeds - Laminaria (a kelp), and Fucus, (rockweed), are
common intertidal seaweeds - Nereocystis and Macrocystis often form
forest-like thickets in deeper waters - Sargassum forms floating masses where other
organisms find shelter - Harvested for food and fertilizer
- Macrocystis is source of algin, a thickener for
foods
24The Phaeophyta
- Laminaria shows tissue differentiation
- Transport organic nutrients in a tissue
resembling phloem - Life cycle
- Most brown algae have alternation of generations
- In some species of Fucus
- Meiosis produces gametes instead of spores
- The adult is always diploid, as in animals
25Diversity of ProtistsYellow-green Algae The
Chrysophyta
- Diatoms (formerly Bacillariophyta) are the most
numerous unicellular algae in the oceans - Significant portion of phytoplankton
- Cell wall
- Two valves, with the larger valve acting as a lid
(like a mint tin) - Contains silica
- Diatomaceous earth used as
- Filtering agents
- Sound-proofing materials
- Polishing abrasives
26Diversity of ProtistsDinoflagellates The
Pyrrophyta
- About 4,000 species of unicellular aquatic and
marine organisms - Morphology
- Cell is usually bounded by protective cellulose
plates impregnated with silicates - Typically with two flagella
- One in a longitudinal groove with its distal end
free - The other lies in a transverse groove that
encircles the organism - Symbiotic dinoflagellates in corals called
zooxanthellae - Dinoflagellates provide their host with organic
nutrients - Corals provide wastes that fertilize the algae
- Some lack chloroplasts and are parasitic
- Gymnodinium brevis may cause red tide
- Produce a powerful neurotoxin that has caused
massive fish kills - Consume shellfish during outbreak can cause
respiratory paralysis
27 Diatoms and Dinoflagellates
28 Fish Kill and Dinoflagellate Bloom
29Diversity of ProtistsThe Euglenoids Phylum
Euglenophyta
- Small freshwater unicellular organisms
- Difficult to classify
- Have two flagella and an eyespot (shades a
photoreceptor) - One flagellum much longer than the other
- Projects out of an anterior, vase-shaped
invagination - Called a tinsel flagellum because of hair-like
projections - Cell bounded by flexible pellicle
- Chloroplasts
- Surrounded by three rather than two membranes
- With a pyrenoid which produces an unusual type of
carbohydrate called paramylon
30 Euglena
31Diversity of ProtistsZooflagellates Phylum
Zoomastigophora
- Colorless heterotrophs
- Most symbiotic and many parasitic
- Well known for causing various diseases in humans
- Trypanosoma
- African sleeping sickness - Tsetse fly
- Chagas disease Kissing bug
- Giardia lamblia
- Most common flagellate in human digestive tract
- Causes severe diarrhea
- Cysts are transmitted in contaminated water
- Beavers are important reservoir hosts
- Trichomonas vaginalis
- Sexually transmitted protist,
- Infects urogenital organs a common cause of
vaginitis
32 Zooflagellates
33 Giardia lamblia
34Diversity of ProtistsProtists with Pseudopods
- Pseudopods form when cytoplasm streams forward in
a particular direction - Amoeboids (phylum Rhizopoda) are protists that
move and ingest their food with pseudopods - Phagocytize food
- Entamoeba histolytica - a parasite of the human
colon - Causes amoebic dysentery
- Can be fatal
- Foraminiferans (phylum Foraminifera) and
radiolarians (phlyum Actinopoda) - Both have a skeleton (test) of either calcite or
silica
35 Protists with Pseudopods
36Diversity of ProtistsThe Ciliates Phylum
Ciliophora
- Ciliates (phylum Ciliophora) are among the most
complex of the protozoans - Hundreds of cilia beat in coordinated rhythm
- Most are holozoic, swallowing food whole
- Divide by transverse binary fission during
asexual reproduction - Two nuclei of differing types
- Micronucleus Heredity
- Macronucleus Metabolism
37 Ciliates
38Diversity of ProtistsThe Sporozoans Phylum
Apicomplexa
- Nonmotile obligate parasites
- Most serious parasitic disease of human is
malaria - Plasmodium spp
- Kills 3,000,000 people each year
- Transmitted by mosquito
- Toxoplasma
- Humans get from cats
- Causes birth defects and mental retardation when
pregnant mom exposed
39 Life Cycle of Plasmodium vivax
40Diversity of ProtistsSlime Molds
- Plasmodial Slime Molds - Phylum Myxomycota
- Body in the form of a plasmodium
- Diploid, multinucleated, cytoplasmic mass
- Enveloped by a slimy sheath
- Eventually produces sporangium which in turn
produces spores - Cellular Slime Mold - Phylum Acrasiomycota
- Body in the form of individual amoeboid cells
- Later aggregate into pseudoplasmodium which then
forms sporangium spores
41 Plasmodial Slime Molds
42Diversity of ProtistsWater Molds - Phylum
Oomycota
- Most live in the water
- Phylum name refers to the enlarged tips (called
oogonia) where eggs are produced - Body filamentous, appearing like true Fungi
- Cell walls largely of cellulose rather than
chitin - The organism is diploid (not haploid as in the
fungi) - Phytophthora infestans caused the 1840s potato
famine in Ireland - Saprolegnia is often seen as a white, cotton-like
coating on dead aquarium fish
43Water Mold
44Review
- Protist Biology
- Protist Evolution
- Protist Diversity
- Green Algae
- Red Algae
- Brown Algae
- Diatoms
- Dinoflagellates
- Protist Diversity, cont.
- Euglenoids
- Zooflagellates
- Pseudopods
- Ciliates
- Sporozoans
- Slime Molds
- Water Molds
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